1. Field of the Invention
This invention relates to an illuminating device and a projection type display apparatus such as a liquid crystal projector using the same.
2. Related Background Art
Heretofore, as the illuminating device of a projection type display apparatus, one as shown in FIG. 6 of the accompanying drawings which comprises a combination of a light-emitting tube 1 and a parabolic mirror 19 has been popular.
In FIG. 6, white light emitted from the light-emitting portion 1c of the light-emitting tube 1 (light source) is converted into a substantially parallel light by the parabolic mirror 19, and the light source image of the light-emitting tube 1 is formed at the center of each frame of a second lens array 4 by a first lens array 3. The focal lengths of the first lens array 3 and the second lens array 4 are substantially equal to each other, and the spacing between the first lens array 3 and the second lens array 4 is a spacing substantially equal to the focal length of the first lens array 3.
The light beam condensed by the first lens array 3 is separated into a P wave and an S wave by the polarization separating layer 5B of a polarization converting element 5, and the S wave is reflected by the polarization separating layer 5B, and is further reflected by an adjacent polarization separating layer 5B, whereby it emerges from the gap of a xcex/2 phase difference plate 5A disposed like a bamboo-blind at the emergence side of the polarization converting element 5. The P wave is transmitted through the polarization separating layer 5B and is further transmitted through the xcex/2 phase difference plate 5A, whereby it is phase-converted and emerges with the direction of its polarization axis uniformized to the S wave. Thereby the light beam emerging from the polarization converting element 5 all become polarized lights (S waves) having polarization axes in the same direction. The reference character 5C designates a bamboo-blind-like light-intercepting plate.
The light beam emerging from the polarization converting element 5 is deflected by a first condenser lens 6, and is modulated into R, G and B colors, which are superposed on the display portions 8R, 8G and 8B of an image modulating device comprising a liquid crystal panel. That is, of the light beam emerging from the first condenser lens 6, red light is reflected by a dichroic mirror DM1 and the remaining green light and blue light are transmitted therethrough. The red light reflected by the dichroic mirror DM1 is directed to the display portion 8R of an image modulating device for red through the intermediary of a reflecting mirror M1 and a second condenser lens 7R. The light transmitted through the dichroic mirror DM1 is separated into green and blue by a dichroic mirror DM2. The green light is reflected by the dichroic mirror DM2, and is directed to the display portion 8G of an image modulating device for green through a second condenser lens 7G. The blue light transmitted through the dichroic mirror DM2 is condensed by a third condenser lens 11, is reflected by a reflecting mirror M2, and is directed to the display portion 8B of an image modulating device for blue by a relay lens 12 through the intermediary of a reflecting mirror M3 and a second condenser lens 7B.
In FIG. 6, the reference character P1 designates an incidence side polarizing plate, and the reference character P2 denotes an emergence side polarizing plate. The second condenser lenses 7R, 7G and 7B are for condensing the light beam emerging from the first condenser lens 6 onto the entrance pupil of a projection lens 10. A cross dichroic prism 9 is disposed between the display portions 8R, 8G, 8B of the image modulating devices and a projection lens 10 to effect color combination. The projection lens 10 is designed to be telecentric relative to the display portions 8R, 8G and 8B of the image modulating devices, and is designed such that the angle of incidence on the dichroic film surface of the cross dichroic prism 9 is constant everywhere on the dichroic film, and is designed such that the color irregularity by any change in the angle of incidence of the dichroic film does not occur. The light beams modulated by the display portions 8R, 8G and 8B of the image modulating devices are color-combined by the cross dichroic prism 9, and are enlargedly projected onto a screen, not shown, by the projection lens 10.
Also, a projection type display apparatus using a light source device including a combination of a plurality of light sources, a plurality of reflecting mirrors and a pair of lens arrays to increase the brightness of an image on the screen is proposed in Japanese Laid-Open Patent Application No. 6-265887, and it is conceived to use such a light source device in the liquid crystal projector of FIG. 6.
If two light sources and a reflecting mirror for disposing the two light sources at a focal position are simply arranged in front of a first lens array 3, unless the focal length of the reflecting mirror is greatly shortened, a desired angle for introducing the lights emitted from the light sources is not obtained, and consequently the degree of parallelism of the light beams entering the first lens array 3 is aggravated, and when the light source portion of the aforementioned Japanese Laid-Open Patent Application No. 6-265887 is used as the light source portion of FIG. 6, the eclipse at the light intercepting portion 5C of a polarization converting element 5 increases and the illumination efficiency becomes reduced. Therefore, it has been found that in spite of the two light sources being used, the increase in quantity of light is only up to the order of 40% as compared with a case where a light source is used.
It is the object of the present invention to realize an improvement in the illuminating efficiency when a plurality of light sources are used.
To solve the above-noted problem, in the present invention, in an illuminating device wherein a plurality of light sources are arranged in a direction perpendicular to an optical axis, an illuminating optical system for illuminating a surface to be illuminated with lights from said plurality of light sources, said illuminating optical system including an optical system in which an action of compressing the lights in a direction of arrangement of said plurality of light sources is stronger than an action of compressing the lights in a direction perpendicular to the direction of arrangement of said plurality of light sources. The illuminating device of the present invention is an illuminating device wherein lights emitted from a plurality of light sources are made to enter a lens array system and illumination is effected by the lights from this lens array system, an optical system in which the action of compressing the lights in the direction of arrangement of the plurality of light sources is greater than the action of compressing the lights in a direction perpendicular thereto is provided between the plurality of light sources and the lens array system. The lens array system is provided with at least one fly-eye lens or at least one lenticular lens.
The illuminating device of the present invention is an illuminating device in which lights emitted from a plurality of light sources are substantially parallel lights and are made to enter a lens array system, and illumination is effected by the lights from the lens array system, characterized in that an optical system in which the action of compressing the incident light in the direction of arrangement of the plurality of light sources is greater than the action of compressing the incident light in a direction perpendicular thereto is provided between the light sources and the lens array system.
In the above-described illuminating device, the plurality of light sources are arranged in the lengthwise direction of a frame of lens constituting the lens array system.
Also, the illuminating device of the present invention is an illuminating device in which lights emitted from a plurality of light sources are substantially parallel lights and are made to enter a lens array system, and illumination is effected by the lights passed from the lens array system through a polarization converting element, characterized in that an optical system in which the action of compressing the incident light in the direction of arrangement of the plurality of light sources is greater than the action of compressing the incident light in a direction perpendicular thereto is provided between the light sources and the lens array system.
Also, the illuminating device of the present invention is an illuminating device in which illumination is effected by lights emitted from a plurality of light sources and passed through a polarization converting element, characterized in that the plurality of light sources are arranged in a direction orthogonal to an incidence plane with respect to the light dividing surface of the element.
In the above-described illuminating device, the plurality of light sources are arranged in a direction perpendicular to the lengthwise direction of a frame of lens constituting the lens array system.
In the above-described illuminating device, the lens array system has at least one fly-eye lens or at least one lenticular lens.
Also, the illuminating device of the present invention is an illuminating device characterized by the provision of a plurality of lamps (light sources), a plurality of first optical systems for converting lights emitted from the lamps into substantially parallel lights, a second optical system in which the action of compressing the light beam is the direction of arrangement of the plurality of lamps is greater than the action of compressing the light beam in a direction perpendicular thereto, a third optical system comprised of a lens array having a plurality of lenses, and a fourth optical system comprised of a lens array having a plurality of lenses, the second optical system being disposed between the lamps and the third optical system.
In the above-described illuminating device, the plurality of lamps and first optical systems are arranged in the lengthwise direction of a frame of lens constituting the fourth optical system.
Also, the illuminating device of the present invention is an illuminating device characterized by the provision of a plurality of lamps, a plurality of first optical systems for converting lights emitted from the lamps into substantially parallel lights, a second optical system in which the action of compressing the light beam in the direction of arrangement of the plurality of lamps is greater than the action of compressing the light beam in a direction perpendicular thereto, a third optical system comprised of a lens array having a plurality of lenses, a fourth optical system comprised of a lens array having a plurality of lenses, and a bamboo-blind-like polarization converting element, the second optical system being disposed between the light sources and the third optical system.
In the above-described illuminating device, the plurality of lamps and first optical systems are arranged in a direction perpendicular to the lengthwise direction of a frame of lens constituting the fourth optical system.
The above-described illuminating device further has a fifth optical system having the action of narrowing the optical axis interval of the plurality of first optical systems between the plurality of first optical systems and the second optical system.
In the above-described illuminating device, the centers of openings in the first optical systems and the optical axes of the first optical systems do not coincide with each other.
In the above-described illuminating device, the first optical systems are parabolic mirrors.
In the above-described illuminating device, the following conditional expression is satisfied:
3 less than DL/Fp less than 6,
where DL is the interval between the plurality of light sources or lamps, and fp is the second focal length of the parabolic mirrors.
In the above-described illuminating device, the second optical system includes a positive cylindrical lens having positive refractive power in the direction of arrangement of the plurality of lamps arranged in succession from the lamps side, and a negative cylindrical lens having negative refractive power in the direction of arrangement of the plurality of lamps.
In the above-described illuminating device, the positive cylindrical lens is stronger in the refractive power of the light source side lens surface thereof than in that of the other lens surface thereof, and the negative cylindrical lens is stronger in the refractive power of the third optical system side lens surface thereof than in that of the other lens surface thereof.
In the above-described illuminating device, the following conditional expression is satisfied:
0.5 less than xe2x88x92fs2/fs1 less than 0.9,
where fs1 is the focal length of the positive cylindrical lens in the direction of arrangement of the plurality of light sources, and fs2 is the focal length of the negative cylindrical lens in the direction of arrangement of the plurality of lamps.
In the above-described illuminating device, a condensing element for rendering the plurality of light sources or lamps conjugate with one another is disposed between adjacent ones of the plurality of light sources.
In the above-described illuminating devices, each of said plurality of light sources includes a lamp unit having a lamp and a parabolic mirror, and the optical axis of each lamp unit is parallel with said optical axis.
Also, the projection type display apparatus of the present invention includes one of the above-described illuminating devices for illuminating an image forming element.